Data de-duplication

ABSTRACT

A new snapshot of a storage volume is created by suppressing write requests. Once pending write requests from the computing nodes are completed, storage nodes create a new snapshot for the storage volume by allocating a new segment to the new snapshot. Subsequent write requests to the storage volume are then performed on the segments allocated to the new snapshot. An orchestration layer implements a bundled application that is provisioned with storage volumes and containers. A snapshot of the application may be created and used to rollback or clone the application. De-duplication may be performed by creating a signature map and identifying duplicated blocks. Blocks of segments containing duplicated blocks are copied to pool segments and metadata of those segments of the same logical storage unit may be consolidated to pool metadata segments. The identification of duplicate blocks may be performed in a cloud computing platform.

BACKGROUND Field of the Invention

This invention relates to removing duplicated data in a distributed storage and computation system.

Background of the Invention

In many contexts, it is helpful to eliminate data that is duplicative. This reduces the amount of storage required to store data and further reduces write amplification in append-only storage schemes. De-duplication further reduces processing required to perform garbage collection.

The systems and methods disclosed herein provide an improved approach for implementing de-duplication.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of a network environment for implementing methods in accordance with an embodiment of the present invention;

FIG. 2 is a process flow diagram of a method for coordinating snapshot creation with compute nodes and storage nodes in accordance with an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating the storage of data within a storage node in accordance with an embodiment of the present invention;

FIG. 4 is a process flow diagram of a method for processing write requests in a storage node in accordance with an embodiment of the present invention;

FIG. 5 is a process flow diagram of a method for processing a snapshot instruction by a storage node in accordance with an embodiment of the present invention;

FIG. 6 is a process flow diagram of a method for performing garbage collection on segments in accordance with an embodiment of the present invention;

FIG. 7 is a process flow diagram of a method for reading data from a snapshot in accordance with an embodiment of the present invention;

FIG. 8 is a process flow diagram of a method for cloning a snapshot in accordance with an embodiment of the present invention;

FIG. 9 illustrates a snapshot hierarchy created in accordance with an embodiment of the present invention;

FIG. 10 is a process flow diagram of a method for rolling back to a prior snapshot in accordance with an embodiment of the present invention;

FIG. 11 illustrates the snapshot hierarchy of FIG. 9 as modified according to the method of FIG. 10 in accordance with an embodiment of the present invention;

FIG. 12 is a process flow diagram of a method for reading from a clone volume in accordance with an embodiment of the present invention;

FIG. 13 is a schematic block diagram of components for implementing orchestration of multi-role applications in accordance with an embodiment of the present invention;

FIG. 14 is a process flow diagram of a method for orchestrating the deployment of a multi-role application in accordance with an embodiment of the present invention;

FIG. 15 is a process flow diagram of a method for implementing provisioning constraints in accordance with an embodiment of the present invention;

FIG. 16 is a process flow diagram of a method for creating a snapshot of a multi-role application in accordance with an embodiment of the present invention;

FIG. 17 is a process flow diagram of a method for rolling back a multi-role application in accordance with an embodiment of the present invention;

FIG. 18A is a schematic diagram illustrating an initial stage of performing de-duplication of storage segments in accordance with an embodiment of the present invention;

FIG. 18B is a schematic diagram illustrating modifications to segments performed during de-duplication in accordance with an embodiment of the present invention;

FIG. 18C illustrates an initial stage of performing de-duplication in conjunction with a cloud computing platform in accordance with an embodiment of the present invention;

FIG. 19 is a process flow diagram of a method for performing de-duplication in accordance with an embodiment of the present invention;

FIG. 20 is a process flow diagram of a method for performing de-duplication in conjunction with a cloud computing platform in accordance with an embodiment of the present invention;

FIG. 21 is a process flow diagram of a method for processing read requests on pool segments in accordance with an embodiment of the present invention; and

FIG. 22 is a schematic block diagram of an example computing device suitable for implementing methods in accordance with embodiments of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1, the methods disclosed herein may be performed using the illustrated network environment 100. The network environment 100 includes a storage manager 102 that coordinates the creation of snapshots of storage volumes and maintains records of where snapshots are stored within the network environment 100. In particular, the storage manager 102 may be connected by way of a network 104 to one or more storage nodes 106, each storage node having one or more storage devices 108, e.g. hard disk drives, flash memory, or other persistent or transitory memory. The network 104 may be a local area network (LAN), wide area network (WAN), or any other type of network including wired, fireless, fiber optic, or any other type of network connections.

One or more compute nodes 110 are also coupled to the network 104 and host user applications that generate read and write requests with respect to storage volumes managed by the storage manager 102 and stored within the memory devices 108 of the storage nodes 108.

The methods disclosed herein ascribe certain functions to the storage manager 102, storage nodes 106, and compute node 110. The methods disclosed herein are particularly useful for large scale deployment including large amounts of data distributed over many storage nodes 106 and accessed by many compute nodes 110. However, the methods disclosed herein may also be implemented using a single computer implementing the functions ascribed herein to some or all of the storage manager 102, storage nodes 106, and compute node 110.

Referring to FIG. 2, the illustrated method 200 may be performed in order to invoke the creation of a new snapshot. Other than a current snapshot, which is still subject to change, a snapshot captures the state of a storage volume at a moment in time and is preferably not altered in response to subsequent writes to the storage volume.

The method 200 includes receiving, by the storage manager 102 a request to create a new snapshot for a storage volume. A storage volume as referred to herein may be a virtual storage volume that may divided into individual slices. For example, storage volumes as described herein may be 1 TB and be divided into 1 GB slices. In general, a slice and its snapshot are stored on a single storage node 106, whereas a storage volume may have the slices thereof stored by multiple storage nodes 106.

The request received at step 202 may be received from a human operator or generated automatically, such as according to backup scheduler executing on the storage manager 102 or some other computing device. The subsequent steps of the method 200 may be executed in response to receiving 202 the request

The method 200 may include transmitting 204 a quiesce instruction to all compute nodes 110 that are associated with the storage volume. For example, all compute nodes 110 that have pending write requests to the storage volume. In some embodiments, the storage manager 102 may store a mapping of compute nodes 110 to a particular storage volume used by the compute nodes 110. Accordingly, step 204 may include sending 204 the quiesce instruction to all of these compute nodes. Alternatively, the instruction may be transmitted 204 to all compute nodes 110 and include an identifier of the storage volume. The compute nodes 110 may then suppress any write instructions referencing that storage volume.

The quiesce instruction instructs the compute nodes 110 that receive it to suppress 206 transmitting write requests to the storage nodes 106 for the storage volume referenced by the quiesce instruction. The quiesce instruction may further cause the compute nodes 110 that receive it to report 208 to the storage manager 102 when no write requests are pending for that storage volume, i.e. all write requests issued to one or more storage nodes 106 and referencing slices of that storage volume have been acknowledged by the one or more storage nodes 106.

In response to receiving the report of step 208 from one or more compute nodes, e.g. all compute nodes that are mapped to the storage node that is the subject of the snapshot request of step 202, the storage manager 102 transmits 210 an instruction to the storage nodes 106 associated with the storage volume to create a new snapshot of that storage volume. Step 210 may further include transmitting 210 an instruction to the compute nodes 110 associated with the storage volume to commence issuing write commands to the storage nodes 106 associated with the storage volume. In some embodiments, the instruction of step 110 may include an identifier of the new snapshot. Accordingly, subsequent input/output operations (IOPs) transmitted 214 from the compute nodes may reference that snapshot identifier. Likewise, the storage node 106 may associate the snapshot identifier with data subsequently written to the storage volume, as described in greater detail below.

In response to receiving 210 the instruction to create a new snapshot, each storage node 106 finalizes 212 segments associated with the current snapshot, which may include performing garbage collection, as described in greater detail below. In addition, subsequent IOPs received by the storage node may also be processed 216 using the new snapshot as the current snapshot, as is also described in greater detail below.

The storage node 102 may further manage errors in the method 200. For example, it may occur that a compute node 110 fails to quiesce. In such instances, the storage node 102 may be programmed to abort the creation of a new snapshot. For example, if a compute node 110 to which the storage volume is mounted fails to quiesce within a timeout period, the storage node 102 may abort the method 200 and retry, such as after a wait period or in response to an instruction to do so from an administrator.

Referring to FIG. 3, the method by which slices are allocated, reassigned, written to, and read from may be understood with respect to the illustrated data storage scheme. The data of the storage scheme may be stored in transitory or persistent memory of the storage node 106, such as in the storage devices 108.

For each logical volume, the storage manager 102 may store and maintain a volume map 300. For each slice in the logical volume, the volume map may include an entry including a node identifier 302 identifying the storage node 106 to which the slice is assigned and an offset 304 within the logical volume at which the slice begins. In some embodiments, slices are assigned both to a storage node 106 and a specific storage device hosted by the storage node 106. Accordingly, the entry may further include a disk identifier of the storage node 106 referencing the specific storage device to which the slice is assigned.

The remaining data structures of FIG. 3 are stored on each storage node 106. The storage node 106 may store a slice map 308. The slice map 308 may include entries including a local slice identifier 310 that uniquely identifies each slice of the storage node 106, e.g. each slice of each storage device hosted by the storage node 106. The entry may further include a volume identifier 312 that identifies the logical volume to which the local slice identifier 310 is assigned. The entry may further include the offset 304 within the logical volume of the slice of the logical volume assigned to the storage node 106.

In some embodiments, an entry in the slice map 308 is created for a slice of the logical volume only after a write request is received that references the offset 304 for that slice. This further supports the implementation of overprovisioning such that slices may be assigned to a storage node 106 in excess of its actual capacity since the slice is only tied up in the slice map 308 when it is actually used.

The storage node 106 may further store and maintain a segment map 314. The segment map 314 includes entries either including or corresponding to a particular physical segment identifier (PSID) 316. For example, the segment map 314 may be in an area of memory such that each address in that area corresponds to one PSID 316 such that the entry does not actually need to include the PSID 316. The entries of the segment map 314 may further include a slice identifier 310 that identifies a local slice of the storage node 106 to which the PSID 316 has been assigned. The entry may further include a virtual segment identifier (VSID) 318. As described in greater detail below, each time a segment is assigned to logical volume and a slice of a logical volume, it may be assigned a VSID 318 such that the VSIDs 318 increase in value monotonically in order of assignment. In this manner, the most recent PSID 316 assigned to a logical volume and slice of a logical volume may easily be determined by the magnitude of the VSIDs 318 mapped to the PSIDs 316. In some embodiments, VSIDs 318 are assigned in a monotonically increasing series for all segments assigned to volume ID 312. In other embodiments, each offset 304 and its corresponding slice ID 310 is assigned VSIDs separately, such that each slice ID 310 has its own corresponding series of monotonically increasing VSIDs 318 assigned to segments allocated to that slice ID 310.

The entries of the segment map 314 may further include a data offset 320 for the PSID 316 of that entry. As described in greater detail below, when data is written to a segment it may be written at a first open position from a first end of the segment. Accordingly, the data offset 320 may indicate the location of this first open position in the segment. The data offset 320 for a segment may therefore be updated each time data is written to the segment to indicate where the new first open position is.

The entries of the segment map 314 may further include a metadata offset 322. As described in detail below, for each write request written to a segment, a metadata entry may be stored in that segment at a first open position from a second end of the segment opposite the first end. Accordingly, the metadata offset 322 in an entry of the segment map 314 may indicate a location of this first open position of the segment corresponding to the entry.

Each PSID 316 corresponds to a physical segment 324 on a device hosted by the storage node 106. As shown, data payloads 326 from various write requests are written to the physical segment 324 starting from a first end (left) of the physical segment. The physical segment may further store index pages 328 such that index pages are written starting from a second end (right) of the physical segment 324.

Each index page 328 may include a header 330. The header 330 may be coded data that enables identification of a start of an index page 328. The entries of the index page 328 each correspond to one of the data payloads 326 and are written in the same order as the data payloads 326. Each entry may include a logical block address (LBA) 332. The LBA 332 indicates an offset within the logical volume to which the data payload corresponds. The LBA 332 may indicate an offset within a slice of the logical volume. For example, inasmuch as the PSID 316 is mapped to a slice ID 310 that is mapped to an offset 304 within a particular volume ID 312, maps 308 and 314, and an LBA 332 within the slice may be mapped to the corresponding offset 304 to obtain a fully resolved address within the logical volume.

In some embodiments, the entries of the index page 328 may further include a physical offset 334 of the data payload 326 corresponding to that entry. Alternatively or additionally, the entries of the index page 328 may include a size 336 of the data payload 326 corresponding to the entry. In this manner, the offset to the start of a data payload 326 for an entry may be obtained by adding up the sizes 336 of previously written entries in the index pages 328.

The metadata offset 322 may point to the last index page 328 (furthest from right in illustrated example) and may further point to the first open entry in the last index page 328. In this manner, for each write request, the metadata entry for that request may be written to the first open position in the last index page 328. If all of the index pages 328 are full, a new index page 328 may be created and stored at the first open position from the second end and the metadata for the write request may be added at the first open position in that index page 328.

The storage node 106 may further store and maintain a block map 338. A block map 338 may be maintained for each logical volume and/or for each slice offset of each logical volume, e.g. for each local slice ID 310 which is mapped to a slice offset and logical volume by slice map 308. The entries of the block map 338 map include entries corresponding to each LBA 332 within the logical volume or slice of the logical volume. The entries may include the LBA 332 itself or may be stored at a location within the block map corresponding to an LBA 332.

The entry for each LBA 332 may include the PSID 316 identifying the physical segment 324 to which a write request referencing that LBA was last written. In some embodiments, the entry for each LBA 332 may further indicate the physical offset 334 within that physical segment 324 to which the data for that LBA was written. Alternatively, the physical offset 324 may be obtained from the index pages 328 of that physical segment. As data is written to an LBA 332, the entry for that LBA 332 may be overwritten to indicate the physical segment 324 and physical offset 334 within that segment 324 to which the most recent data was written.

In embodiments implementing multiple snapshots for a volume and slice of a volume, the segment map 314 may additionally include a snapshot ID 340 identifying the snapshot to which the PSID 316 has been assigned. In particular, each time a segment is allocated to a volume and slice of a volume, the current snapshot identifier for that volume and slice of a volume will be included as the snapshot ID 340 for that PSID 316.

In response to an instruction to create a new snapshot for a volume and slice of a volume, the storage node 106 will store the new current snapshot identifier, e.g. increment the previously stored current snapshot ID 340, and subsequently allocated segments will include the current snapshot ID 340. PSIDs 316 that are not filled and are allocated to the previous snapshot ID 340 may no longer be written to. Instead, they may be finalized or subject to garbage collection (see FIGS. 5 and 6).

FIG. 4 illustrates a method 400 for executing write instructions by a storage node 106, such as write instructions received from an application executing on a compute node 110.

The method 400 includes receiving 402 a write request. The write request may include payload data, payload data size, and an LBA as well as fields such as a slice identifier, a volume identifier, and a snapshot identifier. Where a slice identifier is included, the LBA may be an offset within the slice, otherwise the LBA may be an address within the storage volume.

The method 400 may include evaluating 404 whether a PSID 316 is allocated to the snapshot referenced in the write request and whether the physical segment 324 corresponding to the PSID 316 (“the current segment”) has space for the payload data. In some embodiments, as write requests are performed with respect to a PSID 316, the amount of data written as data 326 and index pages 328 may be tracked, such as by way of the data offset 320 and metadata offset 322 pointers. Accordingly, if the amount of previously-written data 326 and the number of allocated index pages 328 plus the size of the payload data and its corresponding metadata entry exceeds the capacity of the current segment it may be determined to be full at step 404.

If the current segment is determined 404 to be full, the method 400 may include allocating 406 a new PSID 316 as the current PSID 316 and its corresponding physical segment 324 as the current segment for the snapshot referenced in the write request. In some embodiments, the status of PSIDs 316 of the physical storage devices 108 may be flagged in the segment map 314 as allocated or free as a result of allocation and garbage collection, which is discussed below. Accordingly, a free PSID 316 may be identified in the segment map 314 and flagged as allocated.

The segment map 314 may also be updated 408 to include a slice ID 310 and snapshot ID 340 mapping the current PSID 316 to the snapshot ID, volume ID 312, and offset 304 included in the write request. Upon allocation, the current PSID 316 may also be mapped to a VSID (virtual segment identifier) 318 that will be a number higher than previously VSIDs 318 such that the VSIDs increase monotonically, subject, of course, to the size limit of the field used to store the VSID 318. However, the size of the field may be sufficiently large that it is not limiting in most situations.

The method 400 may include writing 410 the payload data to the current segment. As described above, this may include writing 410 payload data 326 to the free location closest to the first end of the current segment.

The method 400 may further include writing 412 a metadata entry to the current segment. This may include writing the metadata entry (LBA, size) to the first free location closest to the second end of the current segment. Alternatively, this may include writing the metadata entry to the first free location in an index page 328 that has room for it or creating a new index page 328 located adjacent a previous index page 328. Steps 410, 412 may include updating one or more pointers or table that indicates an amount of space available in the physical segment, such as a pointer 320 to the first free address closest to the first end and a pointer 322 to the first free address closest to the second end, which may be the first free address before the last index page 328 and/or the first free address in the last index page. In particular, these pointers may be maintained as the data offset 320 and metadata offset in the segment map 314 for the current PSID 316.

The method 400 may further include updating 416 the block map 338 for the current snapshot. In particular, for each LBA 332 referenced in the write request, an entry in the block map 338 for that LBA 332 may be updated to reference the current PSID 316. A write request may write to a range of LBAs 332. Accordingly, the entry for each LBA 332 in that range may be updated to refer to the current PSID 316.

Updating the block map 338 may include evaluating 414 whether an entry for a given LBA 332 referenced in the write request already exists in the block map 338. If so, then that entry is overwritten 418 to refer to the current PSID 316. If not, an entry is updated 416 in the block map 318 that maps the LBA 332 to the current PSID 316. In this manner, the block map 338 only references LBAs 332 that are actually written to, which may be less than all of the LBAs 332 of a storage volume or slice. In other embodiments, the block map 338 is of fixed size and includes an entry for each LBA 332 regardless of whether it has been written to previously. The block map 338 may also be updated to include the physical offset 334 within the current segment to which the data 326 from the write request was written.

In some embodiments, the storage node 106 may execute multiple write requests in parallel for the same LBA 332. Accordingly, it is possible that a later write can complete first and update the block map 338 whereas a previous write request to the same LBA 332 completes later. The data of the previous write request is therefore stale and the block map 338 should not be updated.

Suppressing of updating the block map 338 may be achieved by using the VSIDs 318 and physical offset 334. When executing a write request for an LBA, the VSID 318 mapped to the segment 324 and the physical offset 334 to which the data is to be, or was, written may be compared to the VSID 318 and offset 334 corresponding to the entry in the block map 338 for the LBA 332. If the VSID 318 mapped in the segment map 314 to the PSID 316 in the entry of the block map 338 corresponding to the LBA 332, then the block map 338 will not be updated. Likewise, if the VSID 318 corresponding to the PSID 316 in the block map 338 is the same as the VSID 318 for the write request and the physical offset 334 in the block map 338 is higher than the offset 334 to which the data of the write request is to be or was written, the block map 338 will not be updated for the write request.

As a result of steps 414-418, the block map 338 only lists the PSID 316 where the valid data for a given LBA 332 is stored. Accordingly, only the index pages 328 of the physical segment 324 mapped to the PSID 316 listed in the block map 338 need be searched to find the data for a given LBA 332. In instances where the physical offset 334 is stored in the block map 338, no searching is required.

FIG. 5 illustrates a method 500 executed by a storage node 106 in response to the new snapshot instruction of step 210 for a storage volume. The method 500 may be executed in response to an explicit instruction to create a new snapshot or in response to a write request that includes a new snapshot ID 340. The method 500 may also be executed with respect to a current snapshot that is still being addressed by new write requests. For example, the method 500 may be executed periodically or be triggered based on usage.

The method 500 may include allocating 502 a new PSID 316 and its corresponding physical segment 324 as the current PSID 316 and current segment for the storage volume, e.g., by including a slice ID 310 corresponding to a volume ID 312 and offset 304 included in the new snapshot instruction or the write request referencing the new snapshot ID 340. Allocating 502 a new segment may include updating 504 an entry in the segment map 314 that maps the current PSID 316 to the snapshot ID 340 and a slice ID 310 corresponding to a volume ID 312 and offset 304 included in the new snapshot instruction.

As noted above, when a PSID 316 is allocated, the VSID 318 for that PSID 316 will be a number higher than all VSIDs 318 previously assigned to that volume ID 312, and possibly to that slice ID 310 (where slices have separate series of VSIDs 318). The snapshot ID 340 of the new snapshot may be included in the new snapshot instruction or the storage node 106 may simply assign a new snapshot ID that is the previous snapshot ID 340 plus one.

The method 500 may further include finalizing 506 and performing garbage collection with respect to PSIDs 316 mapped to one or more previous snapshots IDs 340 for the volume ID 312 in the segment map 314, e.g., PSIDs 316 assigned to the snapshot ID 340 that was the current snapshot immediately before the new snapshot instruction was received.

FIG. 6 illustrates a method 600 for finalizing and performing garbage collection with respect to segment IDs 340 for a snapshot (“the subject snapshot”), which may include the current snapshot or a previous snapshot. The method 600 may include marking 602 as valid latest-written data for an LBA 332 in the PSID 316 having the highest VSID 318 in the segment map 314 and to which data was written for that LBA 332. Marking 602 data as valid may include making an entry in a separate table that lists the location of valid data or entries for metadata in a given physical segment 324 or setting a flag in the metadata entries stored in the index pages 328 of a physical segment 324, e.g., a flag that indicates that the data referenced by that metadata is invalid or valid.

Note that the block map 338 records the PSID 316 for the latest version of the data written to a given LBA 332. Accordingly, any references to that LBA 332 in the physical segment 324 of a PSID 316 mapped to a lower-numbered VSID 318 may be marked 604 as invalid. For the physical segment 324 of the PSID 316 in the block map 338 for a given LBA 332, the last metadata entry for that LBA 332 may be found and marked as valid, i.e. the last entry referencing the LBA 332 in the index page 328 that is the last index page 328 including a reference to the LBA 332. Any other references to the LBA 332 in the physical segment 324 may be marked 604 as invalid. Note that the physical offset 334 for the LBA 332 may be included in the block map 334, so all metadata entries not corresponding to that physical offset 334 may be marked as invalid.

The method 600 may then include processing 606 each segment ID S of the PSIDs 316 mapped to the subject snapshot according to steps 608-620. In some embodiments, the processing of step 606 may exclude a current PSID 316, i.e. the last PSID 302 assigned to the subject snapshot. As described below, garbage collection may include writing valid data from a segment to a new segment. Accordingly, step 606 may commence with the PSID 316 having the lowest-valued VSID 318 for the subject snapshot. As any segments 324 are filled according to the garbage collection process, they may also be evaluated to be finalized or subject to garbage collection as described below.

The method 600 may include evaluating 608 whether garbage collection is needed for the segment ID S. This may include comparing the amount of valid data in the physical segment 324 for the segment ID S to a threshold. For example, if only 40% of the data stored in the physical segment 324 for the segment ID S has been marked valid, then garbage collection may be determined to be necessary. Other thresholds may be used, such as value between 30% and 80%. In other embodiments, the amount of valid data is compared to the size of the physical segment 324, e.g., the segment ID S is determined to need garbage collection if the amount of valid data is less than X % of the size of the physical segment 324, where X is a value between 30 and 80, such as 40.

If garbage collection is determined 608 not to be needed, the method 600 may include finalizing 610 the segment ID S. Finalizing may include flagging the segment ID S in the segment map 314 as full and no longer available to be written to. This flag may be stored in another table that lists finalized PSIDs 316.

If garbage collection is determined 608 to be needed, then the method 600 may include writing 612 the valid data to a new segment. For example, if the valid data may be written to a current PSID 316, i.e. the most-recently allocated PSID 316 for the subject snapshot, until its corresponding physical segment 324 full. If there is no room in the physical segment 324 for the current PSID 316, step 612 may include assigning a new PSID 316 as the current PSID 316 for the subject snapshot. The valid data, or remaining valid data, may then be written to the physical segment 324 corresponding to the current PSID 316 for the subject snapshot.

Note that writing 612 the valid data to the new segment maybe processed in the same manner as for any other write request (see FIG. 4) except that the snapshot ID used will be the snapshot ID 340 of the subject snapshot, which may not be the current snapshot ID. In particular, the manner in which the new PSID 316 is allocated to the subject snapshot may be performed in the same manner described above with respect to steps 406-48 of FIG. 4. Likewise, the manner in which the valid data is written to the current segment may be performed in the same manner as for steps 410-412 of FIG. 4. In some embodiments, writing of valid data to a new segment as part of garbage collection may also include updating the block map with the new location of the data for an LBA 332, such as according to steps 414-418 of FIG. 4. When the physical segment 324 of the current PSID 316 is found to be full, it may itself be subject to the process 600 by which it is finalized or subject to garbage collection.

After the valid data is written to a new segment, the method 600 may further include freeing 614 the PSID S in the segment map 314, e.g., marking the entry in segment map 314 corresponding to PSID S as free.

The process of garbage collection may be simplified for PSIDs 316 that are associated with the subject snapshot in the segment map 314 but are not listed in the block map 338 with respect to any LBA 332. The physical segments 324 of such PSIDs 316 do not store any valid data. Entries for such PSIDs 316 in the segment map 314 may therefore simply be deleted and marked as free in the segment map 314

FIG. 7 illustrates a method 700 that may be executed by a storage node 106 in response to a read request. The read request may be received from an application executing on a compute node 110. The read request may include such information as a snapshot ID, volume ID (and/or slice ID), LBA, and size (e.g. number of 4 KB blocks to read).

The following steps of the method 700 may be initially executed using the snapshot ID 340 included in the read request as “the subject snapshot,” i.e., the snapshot that is currently being processed to search for requested data. The method 700 includes receiving 702 the read request by the storage node 106 and identifying 704 one or more PSIDs 316 in the segment map 314 assigned to the subject snapshot and searching 706 the metadata entries for these PSIDs 316 for references to the LBA 332 included in the read request.

The searching of step 706 may be performed in order of decreasing VSID 318, i.e. such that the metadata entries for the last allocated PSID 316 is searched first. In this manner, if reference to the LBA 332 is found, the metadata of any previously-allocated PSIDs 316 does not need to be searched.

Searching 706 the metadata for a PSID 316 may include searching one or more index pages 328 of the physical segment 324 corresponding to the PSID 316. As noted above, one or more index pages 328 are stored at the second end of the physical segment 324 and entries are added to the index pages 328 in the order they are received. Accordingly, the last-written metadata including the LBA 332 in the last index page 328 (furthest from the second end of the physical segment 324) in which the LBA 332 is found will correspond to the valid data for that LBA 332. To locate the data 326 corresponding to the last-written metadata for the LBA 332 in the physical segment 324, the sizes 336 for all previously-written metadata entries may be summed to find a start address in the physical segment 324 for the data 326. Alternatively, if the physical offset 334 is included, then the data 326 corresponding to the metadata may be located without summing the sizes 336.

If reference to the LBA 332 is found 708 in the physical segment 324 for any of the PSIDs 316 allocated to the subject snapshot, the data 326 corresponding to the last-written metadata entry including that LBA 332 in the physical segment 324 mapped to the PSID 316 having the highest VSID 318 of all PSIDs 316 in which the LBA is found will be returned 710 to the application that issued the read request.

If the LBA 332 is not found in the metadata entries for any of the PSIDs 316 mapped to subject snapshot, the method 700 may include evaluating 712 whether the subject snapshot is the earliest snapshot for the storage volume of the read request on the storage node 106. If so, then the data requested is not available to be read and the method 700 may include returning 714 a “data not found” message or otherwise indicating to the requesting application that the data is not available.

If an earlier snapshot than the subject snapshot is present for the storage volume on the storage node 106, e.g., there exists at least one PSID 316 mapped to a snapshot ID 340 that is lower than the snapshot ID 340 of the subject snapshot ID, then the immediately preceding snapshot ID 340 will be set 716 to be the subject snapshot and processing will continue at step 704, i.e. the PSIDs 316 mapped to the subject snapshot will be searched for the LBA 332 in the read request as described above.

The method 700 is particularly suited for reading data from snapshots other than the current snapshot that is currently being written to. In the case of a read request from the current snapshot, the block map 338 may map each LBA 332 to the PSID 316 in which the valid data for that LBA 332 is written. Accordingly, for such embodiments, step 704 may include retrieving the PSID 332 for the LBA 332 in the write request from the block map 338 and only searching 706 the metadata corresponding to that PSID 316. Where the block map 338 stores a physical offset 334, then the data is retrieved from that physical offset within the physical segment 314 of the PSID 336 mapped to the LBA 332 of the read request.

In some embodiments, the block map 332 may be generated for a snapshot other than the current snapshot in order to facilitate executing read requests, such as where a large number of read requests are anticipated in order to reduce latency. This may include searching the index pages 328 of the segments 324 allocated to the subject snapshot and its preceding snapshots to identify, for each LBA 332 to which data has been written, the PSID 316 having the highest VSID 318 of the PSIDs 316 having physical segments 324 storing data written to the each LBA 332. This PSID 316 may then be written to the block map 318 for the each LBA 332. Likewise, the physical offset 334 of the last-written data for that LBA 332 within the physical segment 324 for that PSID 316 may be identified as described above (e.g., as described above with respect to steps 704-716).

Referring to FIG. 8, in some instances it may be beneficial to clone a storage volume. This may include capturing a current state of a principal copy of a storage volume and making changes to it without affecting the principal copy of the storage volume. For purposes of this disclosure a “principal copy” or “principal snapshot” of a storage volume refers to an actual production copy that is part of a series of snapshots that is considered by the user to be the current, official, or most up-to-date copy of the storage volume. In contrast, a clone volume is a snapshot created for experimentation or evaluation but changes to it are not intended by the user to become part of the production copy of the storage volume. Stated differently, only one snapshot may be a principal snapshot with respect to an immediately preceding snapshot, independent of the purpose of the snapshot. Any other snapshots that are immediate descendants of the immediately preceding snapshot are snapshots of a clone volume.

The illustrated method 800 may be executed by the storage manager 102 and one or more storage nodes 106 in order to implement this functionality. The method 800 may include receiving 802 a clone instruction and executing the remaining steps of the method 800 in response to the clone instruction. The clone instruction may be received by the storage manager 102 from a user or be generated according to a script or other program executing on the storage manager 102 or a remote computing device in communication with the storage manager 102.

The method 800 may include recording 804 a clone branch in a snapshot tree. For example, referring to FIG. 9, in some embodiments, for each snapshot that is created for a storage volume, the storage manager 102 may create a node S1-S5 in a snapshot hierarchy 900. In response to a clone instruction, the storage manager 102 may create a clone volume and branch to a node A1 representing the clone volume. In the illustrated example, a clone instruction was received with respect to the snapshot of node S2. This resulted in the creation of a clone volume represented by node A1 that branches from node S2. Note node S3 and its descendants are also connected to node S2 in the hierarchy.

In some embodiments, the clone instruction may specify which snapshot the clone volume is of. In other embodiments, the clone instruction may be inferred to be a snapshot of a current snapshot. In such embodiments, a new principal snapshot may be created and become the current snapshot. The previous snapshot will then be finalized and be subject to garbage collection as described above. The clone will then branch from the previous snapshot. In the illustrated example, if node S2 represented the current snapshot, then a new snapshot represented by node S3 would be created. The snapshot of node S2 would then be finalized and subject to garbage collection and the snapshot of the clone volume represented by A1 would be created and node A1 would be added to the hierarchy as a descendent of node S2.

In some embodiments, the clone node A1, and possibly its descendants A2 to A4 (representing subsequent snapshots of the clone volume), may be distinguished from the nodes S1 to S5 representing principal snapshots, such as by means of a flag, a classification of the connection between the node A1 and node S2 that is its immediate ancestor, or by storing data defining node A1 in a separate data structure.

Following creation of a clone volume, other principal snapshots of the storage volume may be created and added to represented in the hierarchy by one or more nodes S2 to S5. A clone may be created of any of these snapshots and represented by additional clone nodes. In the illustrated example, node B1 represents a snapshot of a clone volume that is a clone of the snapshot represented by node S4. Subsequent snapshots of the clone volume are represented by nodes B1 to B3.

Referring again to FIG. 8, the creation of a snapshot for a clone volume on the storage node 106 may be performed in the identical manner as for any other snapshot, such as according to the methods of FIGS. 2 through 6. In particular, one or more segments 806 may be allocated to the clone volume on storage nodes 106 storing slices of the cloned storage volume and mapped to the clone volume. IOPs referencing the clone volume may be executed 808, such as according to the method 400 of FIG. 4.

In some instances, it may be desirable to store snapshots of a clone volume on a different storage node 106 than the principal snapshots. Accordingly, the method 800 may include allocating 806 segments to the clone volume on the different storage node 106. This may be invoked by sending a new snapshot instruction referencing the clone volume (i.e., an identifier of the clone volume) to the different storage node 106 and instructing one or more compute nodes 110 to route IOPs for the clone volume to the different storage node 106.

The storage node 102 may store in each node of the hierarchy, data identifying one or more storage nodes 106 that store data for the snapshot represented by that node of the hierarchy. For example, each node may store or have associated therewith one or more identifiers of storage nodes 106 that store a particular snapshot ID for a particular volume ID. The node may further map one or more slice IDs (e.g., slice offsets) of a storage volume to one storage nodes 106 storing data for that slice ID and the snapshots for that slice ID.

Referring to FIG. 10, one of the benefits of snapshots is the ability to capture the state of a storage volume such that it can be restored at a later time. FIG. 10 illustrates a method 1000 for rolling back a storage volume to a previous snapshot, particularly for a storage volume having one or more clone volumes.

The method 1000 includes receiving 1002, by the storage manager 102, an instruction to rollback a storage volume to a particular snapshot SN. The method 1000 may then include processing 1004 each snapshot that is a represented by a descendent node of the node representing snapshot SN in the snapshot hierarchy, i.e. snapshots SN+1 to SMAX, where SMAX is the last principal snapshot that is a descendent of snapshot SN (each “descendent snapshot”). For each descendent snapshot, processing 1004 may include evaluating 1006 whether the each descendent is an ancestor of a node representing a snapshot of a clone volume. If not, then the storage manager 102 may instruct all storage nodes 106 storing segments mapped to the descendent snapshot to free 1008 these segments, i.e. delete entries from the segment map referencing the descendent snapshot and marking corresponding PSIDs 316 as free in the segment map 314.

If the descendent snapshot is found 1006 to be an ancestor of a snapshot of a clone volume, then step 1008 is not performed and the snapshot and any segments allocated to it are retained.

FIG. 11 illustrates the snapshot hierarchy following execution of the method 1000 with respect to the snapshot represented by node S3. As is apparent, snapshot S5 has been removed from the hierarchy and any segments corresponding to these snapshots will have been freed on one or more storage nodes 106.

However, since node S4 is an ancestor of clone node B1, it is not removed and segments corresponding to it are not freed on one or more storage nodes in response to the roll back instruction. Inasmuch as each snapshot contains only data written to the storage volume after it was created, previous snapshots may be required to recreate the storage volume. Accordingly, the snapshots of nodes S3 to S1 are needed to create the snapshot of the storage volume corresponding to node B1.

Subsequent principal snapshots of the storage volume will be added as descendants of the node to which the storage volume was rolled back. In the illustrated example, a new principal snapshot is represented by node S6 that is an immediate descendent of node S3. Node S4 is only present due to clone node B1 and therefore may itself be classified as a clone node in the hierarchy in response to the rollback instruction of step 1002.

Note that FIG. 11 is a simple representation of a hierarchy. There could be any number of clone volumes, snapshots of clone volumes, clones of clone volumes and descendent snapshots of any snapshots of any clone volume represented by nodes of a hierarchy. Accordingly, to roll back to a particular snapshot of a clone, the method 1000 is the same, except that descendants of a snapshot of a clone volume are treated the same as principal snapshots and clones of any of these descendants are treated the same as a snapshot of a clone volume.

Referring to FIG. 12, the illustrated method 1200 may be used to execute a read request with respect to a storage volume that is represented by a hierarchy generated as described above with respect to FIGS. 8 through 11. The illustrated method 1200 may also be executed with respect to a storage volume that includes only principal snapshots that are distributed across multiple storage nodes, i.e., all the segments corresponding to snapshots of the same slice of the storage volume are not located on the same storage node 106. In that case, the hierarchy stored on the storage manager 102 stores the location of the segments for each snapshot and therefore enables them to be located.

The method 1200 may be executed by a storage node 106 (“the current storage node”) with information retrieved from the storage manager 102 as noted below. The method 1200 may include receiving 1202 a read request, which may include such information as a snapshot ID, volume ID (and/or slice ID), LBA, and size (e.g. number of 4 KB blocks to read).

Note that the read request may be issued by an application executing on a compute node 110. The compute node 110 may determine which storage node 106 to transmit the read request using information from the storage manager 102. For example, the compute node 110 may transmit a request to obtain an identifier for the storage node 102 storing data for a particular slice and snapshot of a storage volume. The storage manager may then obtain an identifier and/or address for the storage node 106 storing that snapshot and slice of the storage volume from the hierarchical representation of the storage volume and return it to the requesting compute node 110. For example, the storage manager 102 may retrieve this information from the node in the hierarchy representing the snapshot included in the read request.

In response to the read request, the current storage node performs the algorithm illustrated by subsequent steps of the method 1200. In particular, the method 1200 may include identifying 1204 segments assigned to the snapshot ID of the read request in the segment (“the subject snapshot”).

The method 1200 may include searching 1206 the metadata of the segments identified in step 1204 for the LBA of the read request. If the LBA is found, the data from the highest numbered segment having the LBA in its metadata is returned, i.e. the data that corresponds to the last-written metadata entry including the LBA.

If the LBA is not found in any of the segments mapped to subject snapshot, then the method 1200 may include evaluating 1212 whether the subject snapshot is the earliest snapshot on the current storage node. If not, then steps processing continues at step 1204 with the previous snapshot set 1214 as the subject snapshot.

Steps 1204-1214 may be performed in the same manner as for steps 704-714 of the method 700, including the various modifications and variations described above with respect to the method 700.

In contrast to the method 700, if the LBA is not found in any of the segments corresponding to the subject snapshot for any of the snapshots evaluated, then the method 1200 may include requesting 1216 a location, e.g. storage node identifier, where an earlier snapshot for the volume ID or slice ID is stored. In response to this request, the storage manager 102 determines an identifier of a storage node 106 storing the snapshot corresponding to the immediate ancestor of the earliest snapshot stored on the current storage node in the hierarchy. The storage manager 102 may determine an identifier of the storage node 106 relating to the immediate-ancestor snapshot and that stores data for a slice ID and volume ID of the read request as recorded for the ancestor nearest ancestor node in the hierarchy of the node corresponding to the earliest snapshot stored on the current storage node.

If the current storage node is found 1218 to be the earliest snapshot for the storage volume ID and/or slice ID of the read request, then the data the storage manager 102 may report this fact to the storage node, which will then return 1220 a message indicating that the requested LBA is not available for reading, such as in the same manner as step 714 of the method 700.

If another storage node stores an earlier snapshot for the volume ID and/or slice ID of the read request, then the read request may be transmitted 1222 to this next storage node by either the current storage node or the storage manager 102. The processing may then continue at step 1202 with the next storage node as the current storage node. The read request transmitted at step 1222 may have a snapshot ID set to the latest snapshot ID for the storage volume ID and or slice ID of the original read request.

The method 1200 may be performed repeatedly across multiple storage nodes 106 until the earliest snapshot is encountered or the LBA of the read request is located.

Referring to FIG. 13, storage according to the above-described methods and systems may be incorporated into an application-orchestration approach. In the illustrates approach, an orchestration layer 1300 implements a bundled application 1302 including a plurality of roles. In the following description, “bundled application” refers to a bundle of applications as implemented using the orchestration layer. A “role” is an instance of an executable that is managed by the orchestration layer as described herein as part of the bundled application. Accordingly, a “role” may itself be a standalone application, such as a database, webserver, blogging application, or any other application. Examples of roles include CASSANDRA, HADOOP, SPARK, DRUID, SQL database, ORACLE database, MONGODB database, WORDPRESS, and the like.

The orchestration layer 1300 may implement a bundled application 1302 defining roles and relationships between roles as described in greater detail below. The bundled application 1302 may include a manifest 1304 that defines the roles of the bundled application 1302, which may include identifiers of roles and possibly a number of instances for each role identified. The manifest 1304 may define dynamic functions define how the number of instances of particular role may grow or shrink depending on usage. The orchestration layer 1300 may then create or remove instances for a role as described below as indicated by usage and one or more functions for that role. The manifest 1304 may define a topology of the bundled application 1302, i.e. the relationship between roles, such as services of a role that are accessed by another role.

The bundled application 1302 may include provisioning 1306. The provisioning 1306 defines the resources of storage nodes 106 and compute nodes 110 required to implement the bundle. The provisioning 1306 may define resources for the bundle as a whole or for individual roles. Resources may include a number of processors (e.g., processing cores), an amount of memory (e.g., RAM (random access memory), an amount of storage (e.g., GB (gigabytes) on a HDD (Hard Disk Drive) or SSD (Solid State Drive)). As described below, these resources may be provisioned in a virtualized manner such that the bundled application 1302 and individual roles 1312 are not informed of the actual location or processing and storage resources and are relieved from any responsibility for managing such resources. In particular, storage resources may be virtualized by the storage manager 102 using the methods described above such that storage volumes are allocated and used without requiring the bundled application 1302 or roles to manage the underlying storage nodes 106 and storage device 108 on which the data of the storage volumes is written.

Provisioning 1306 may include static specification of resources and may also include dynamic provisioning functions that will invoke allocation of resources in response to usage of the bundled application. For example, as a database fills up, additional storage volumes may be allocated. As usage of a bundled application increases, additional processing cores and memory may be allocated to reduce latency.

A bundled application 1302 may further include configuration parameters 1308. Configuration parameters may include variables and settings for each role of the bundle. The configuration parameters are defined by the developer of the role and therefore may include any example of such parameters for any application known in the art. The configuration parameters may be dynamic or static. For example, some parameters may be dependent on resources such as an amount of memory, processing cores, or storage. Accordingly, these parameters may be defined as a function of these resources. The orchestration layer will then update such parameters according to the function in response to changes in provisioning of those resources that are inputs to the function. For example, CASSANDRA defines a variable Max_Heap_Size that is normally set to half the memory limit. Accordingly, as the memory provisioned for a CASSANDRA role increases, the value of Max_Heap_Size may be increased to half the increased memory.

The bundled application 1302 may further include action hooks 1310 for various actions that may be taken with respect to the bundled application and/or particular roles of the bundled applications. Actions may include some or all of stopping, starting, restarting, taking snapshots, cloning, and rolling back to a prior snapshot. For each action, one or more action hooks may be defined. A hook is a programmable routine that is executed by the orchestration layer when the corresponding action is invoked. A hook may specify a script of commands or configuration parameters input to one or more roles in a particular order. Hooks for an action may include a pre-action hook (executed prior to implementing an action), an action hook (executed to actually implement the action), and a post action hook (executed following implementation of the action).

The bundled application 1302 may define a plurality of roles 1312. Each role may include one or more provisioning constraints. As noted above, the bundled application 1302 and roles 1312 are not aware of the underlying storage nodes 106 and compute nodes 110 inasmuch as these are virtualized by the storage manager 102 and orchestration layer 1300. Accordingly, any constraints on allocation of hardware resources may be included in the provisioning constraints 1314. As described in greater detail below, this may include constraints to create separate fault domains in order to implement redundancy and constraints on latency.

The role 1312 may define a name space 1316. A name space 1316 may include variables, functions, services, and the like implemented by a role. In particular, interfaces and services exposed by a role may be included in the name space. The name space may be referenced through the orchestration layer 1300 by an addressing scheme, e.g. <Bundle ID>.<Role ID>.<Name>. In some embodiments, references to the namespace 1316 of another role may be formatted and processed according to the JINJA template engine or some other syntax. Accordingly, each role 1312 may access the variables, functions, services, etc. in the name space 1316 of another role 1312 on order to implement a complex application topology. In some instances, credentials for authorizing access to a role 1312 may be shared by accessing the namespace 1316 of that role.

A role 1312 may further include various configuration parameters 1318 defined by the role, i.e. as defined by the developer that created the executable for the role. As noted above, these parameters 1318 may be set by the orchestration layer 1300 according to the static or dynamic configuration parameters 1308. Configuration parameters may also be referenced in the name space 1316 and be accessible (for reading and/or writing) by other roles 1312.

Each role 1312 may include a container 1320 executing an instance 1322 of the application for that role. The container 1320 may be a virtualization container, such as a virtual machine, that defines a context within which the application instance 1322 executes, facilitating starting, stopping, restarting, and other management of the execution of the application instance 1322. Containers 1320 may include any container technology known in the art such as DOCKER, LXC, LCS, KVM, or the like. In a particular bundled application 1302, there may be containers 1320 of multiple different types in order to take advantage of a particular container's capabilities to execute a particular role 1312. For example, one role 1312 of a bundled application 1302 may execute a DOCKER container 1320 and another role 1312 of the same bundled application 1302 may execute an LCS container 1320. The manifest 1304 and/or provisioning 1306 may define a particular container 1320 of the bundled application 1320 to mount each provisioned storage volume for use by that container 1320.

Note that a bundled application 1302 as configured in the foregoing description may be instantiated and used or may be saved as a template that can be used and modified later.

FIG. 14 illustrates a method 1400 for executing a bundled application 1302 using the orchestration layer 1300. The method 1400 may include provisioning 1402 storage and computation resources according to the provisioning 1306. This may include allocating storage volumes according to the storage requirements, assigning the storage volumes to storage nodes 106, and selecting a compute node 110 or storage node 106 providing the required computational resources (processor cores and memory).

The method 1400 may include creating 1404 role instances for the roles 1312 defined by the bundled application 1302. As described above, this may include creating a container 1320 and instantiating the application instance 1322 of the role 1312 within the container 1320. The order in which instances 1322 are created and started may be defined in the manifest 1304.

The method 1400 may include configuring 1406 each role according to the configuration parameters 1308, including executing any included functions to determine values for dynamic parameters. As noted above, starting a bundled application 1302 may further include setting up 1408 the roles 1312 to reference resources in the name space 1316 of another role 1312. For example, a webserver may be configured to access a database by referencing configuration parameters and services implemented by the database.

The method 1400 may further include executing 1410 any hooks 1310 defined for the initial startup of the bundled applications. Accordingly, pre-startup, startup, and post startup hooks may be executed. Some or all of the functions of steps 1402-1410 may be defined as part of the pre-startup hook. Other functions may also be performed prior to steps 1402-1408 as defined by a pre-startup hook.

The actual commencement of execution of the instances 1322 of the bundled application 1302 may be performed in an order specified by the startup hook and may include performing any attendant functions of these instances 1322 as specified by the startup hook. Following startup, one or more other actions may be performed as specified by the developer in the post-startup hook. These actions may invoke functions of the instances 1322 themselves or executed by the orchestration layer 1300 outside of the instances 1322, such as with respect to an operating system executing the containers 1320 for the instances 1322.

The bundled application 1302 may then be accessed 1412 in order to perform the programmed functionality of the application instances 1322. As usage occurs, processing resources will be loaded and storage may be filled. The method 1400 may further include adjusting 1414 provisioning according to this usage and may performed adjustment to configuration parameters of the roles 1312 according to this provisioning as defined by the provisioning 1306 and configuration functions 1308.

As noted above, instances of roles may also be created or removed according to usage. Accordingly, where indicate by the manifest 1304, instances 1322 for a role 1312 may be created according to steps 1402-1410 throughout execution of the bundled application 1302 as defined by one or more dynamic functions in the manifest 1304 for that role 1312.

Referring to FIG. 15, the illustrated method 1500 may be used to implement provisioning constraints 1314 for a role 1312 or constraints for an entire bundled application 1302. The method 1500 may be executed by the orchestration layer 1300, storage manager 102, or a combination of the two.

The method 1500 may include receiving 1502 the provisioning constraint 1314 for one or more roles 1312 of the bundled application 1302 and determining 1504 whether the constraint 1314 specify one or both of a fault domain constraint and a latency constraint.

If a latency constraint is found 1506 to be included for a role 1312, then computational resources and storage resources to be provisioned for the role 1312 may be constrained 1508 to be co-located. In particular, latency may be specified in terms of (a) a minimum network delay, (b) a minimum network throughput, (c) an explicit constraint to place computation and storage resources in the same subnetwork, or (d) an explicit constraint to place computation and storage resources on the same node, i.e. a hybrid compute and storage node 110, 106 that performs the functions of both types of nodes with a single computer.

This constraint may be passed to the storage manager 102, which then allocates computational and storage requirements according to it. In particular, one or more storage volumes for the role 1312 will be assigned to storage nodes 106 that can either (a) meet the latency requirement with respect to compute nodes 110 allocated to the role 1312 (b) also provide the computational resources required for the role 1312.

If the constrain for a role 1312 is found 1510 to include a fault domain constraint, then storage volumes for the role 1312 may be distributed 1512 among the storage nodes 106 of the distributed storage system 100 according to this requirement. For example, if storage volume B is a redundant (e.g., replica or backup copy) of storage volume A, the fault domain constraint may indicate this fact. Accordingly, the storage manager 102 may assign storage volume B to a different storage node 106 than storage volume A. Various degrees of constraint may be specified. For example, a fault domain constraint may simply require a different storage device 108 but not require a different storage node 106. A fault domain constraint may require that storage nodes 106 to which storage volumes are assigned by in separate subnetworks, different geographic locations, or have some other degree of separation. Similar fault domain constraints may be specified for roles 1312, which may be constrained to execute on different compute nodes 110 in order to provide redundant services and reduce downtime.

The provisioning constraints 1502 based on fault domains and/or latency may be combined with one or more other constraints. For example, a performance constraint (IOPs/second) for a storage node may be imposed. Accordingly, only those compute nodes meeting the performance requirement and the fault domain and/or latency requirements will be selected for provisioning.

As noted above, provisioning 1306 may define a processing requirement, such as a number of processing cores and an amount of storage for a role. Accordingly, compute nodes 110 may be selected at step 1508 such that both the latency requirement and processing requirement are met.

Referring to FIG. 16, the illustrated method 1600 may be executed by the orchestration layer 1302 with respect to a bundled application 1302 in order to create a snapshot of the bundled application 1302 that can be later restored (see the method 1700 of FIG. 17).

The method 1600 may include flushing 1602 application buffers to disk. In many instances, performance of an application is accelerated by maintaining data in a cache in memory, such that data in the cache is accessed and updated without requiring writing to a disk in many instances, as known in the art. Accordingly, this buffer may be flushed 1602 to disk by writing all valid data (i.e., not outdated due to a subsequent write) in the cache to the storage device 108 to which that data is addressed, e.g., to which the storage volume referenced by the data is assigned.

In a like manner, a file system flush may be performed 1604. Performing a file system flush may include ensuring that all IOPs pending to be performed by the file system have been executed, i.e. written to disk. As for step 1602, data written to a cache for the file system this is valid may be written to a storage device 108 to which the data is addressed, e.g., to which the storage volume referenced by the data is assigned.

The method 1600 may then include freezing 1606 the application instances 1322 of each role 1312. In particular, inasmuch as each instance 1322 is executing within container 1320, the containers 1320 for the roles 1312 may be instructed to pause execution of each instance 1322. This may include stopping execution and saving a state of execution of each instance 1322 (state variables, register contents, program pointers, function stack, etc.).

The method 1600 may further include creating 1608 a snapshot of storage volumes provisioned for the bundled application. This may include executing the method 200 of FIG. 2 or any of the above-described approaches for implementing a snapshot of a storage volume.

The method 1600 may further include creating 1610 a topology snapshot for the bundled application 1302. The topology of an application may include some or all of the following information as constituted at the time of executing step 1610 a listing of the roles 1312, which may include one or more instances 1322 of the same role 1322, relationships between application instances 1322 of roles 1312 (name space cross-references, configuration parameters), storage volumes assigned to roles 1312, or other information that describes the topology of the bundled application 1302. Applications may create metadata describing their state of operation. This data may also be saved as part of the topology snapshot.

After the snapshot is created according to the method 1600, the application instances may be restarted and the bundled application 1302 may continue to operate. If desired, the application may then be rolled back to the snapshot created according to the method 1600, as described below with respect to FIG. 17.

FIG. 17 illustrates a method 1700 for rolling back a bundled application 1302 to a snapshot, such as a snapshot created according to the method 1600. The method 1700 may be executed by one or both of the orchestration layer 1300 and the storage manager 102.

The method 1700 includes receiving 1702 a rollback instruction, such as from an administrator desiring to return to a stable version of the bundled application 1302. The remaining steps of the method 1300 may be executed in response to the rollback instruction.

The method 1700 may include rolling 1704 back storage volumes assigned to the bundled application 1302 to the snapshots created for the snapshot of the bundled application 1302 (e.g., at step 1608 of the method 1600). This may include executing the method 1000 of FIG. 10 or performing any other approach for rolling back a storage volume to a prior state.

The method 1700 may include restoring 1706 application instances from the application snapshot. As described above with respect to step 1606 of the method 1600, an application instance 1322 may be frozen. Accordingly, data describing a state of execution of the application instance 1322 may be reloaded into a container 1302 for that instance. If needed, the container for that application instance 1322 may be created and the instance 1322 loaded into it prior to loading the state of execution. This is particularly the case where the number of application instances has changed since the application snapshot was create.

The method 1700 may further include restoring 1708 the application topology saved for the bundled application at step 1610. Accordingly, relationships between application instances 1322 of roles 1312 (name space cross-references, configuration parameters), storage volumes assigned to roles 1312, or other information that describes the topology of the bundled application 1302 may be restored as it was at the time the application snapshot was created

The method 1700 further include executing 1710, 1712, 1714 a pre-restart hook, restart hook, and post restart hook defined for the bundled application. As described above, each hook may be a routine defined by a developer to be executed for a particular action, restarting in this case. In step 1712, execution of the instances 1322 for the roles 1322 may be restarted, along with any other actions specified by the developer in the restart hook.

The bundled application 1302 as restored at steps 1704-1714 may then be accessed 1716 as defined by the programming of the application instances and the restored application topology.

Note that the snapshot of the bundled application 1302 may be restarted on different storage and compute nodes 106, 110 than those on which the bundled application 1302 was executing when the snapshot was created. Accordingly, the application snapshot may be restarted as a clone of the bundled application 1302 or moved to different hardware when executing the method 1700.

In some instances, the hooks of steps 1710, 1712, 1714 may be different when the application snapshot is being restarted as a clone as desired by a developer. For example, a developer may desire to scale the clone application to increase or decrease a number of databases, number of partitions of a database, or other aspect of the clone application. Accordingly, the hooks of steps 1710, 1712, 1714 may implement routines to implement this increase or decrease.

For example, some applications are able to automatically detect the number of partitions of a database. In such instances, some or all of the hooks 1710, 1712, 1714 may reduce the number of partitions in a database of the clone applications and rely on the application to discover this change. In other instances, some or all of the hooks 1710, 1712, 1714 may be programmed to configure an application to access the database with the reduced number of partitions where the application is unable to configure itself.

FIG. 18A illustrates an approach for implementing de-duplication. Segments 1800 may be segments created and managed as described above with respect to FIGS. 1 through 13. Each segment may include a plurality of blocks 1802 of data. In particular, the blocks 1802 may correspond to the payload data 326 shown in FIG. 3. In some embodiments, the blocks 1802 have a fixed size, such as 4 kilobytes (kB). The segments 1800 that are processed during de-duplication may include all the segments belonging to a same storage volume, all the segments on a same storage device 108, all the segments storage on storage devices 108 connected to the same storage node 106, or all segments stored on the storage devices 108 of multiple storage nodes 106.

As also described above with respect to FIG. 3, each segment 1802 include a metadata section 1804 storing metadata entries including an LBA and a physical offset within the segment 1800 at which the block 1802 corresponding to that LBA is written.

Preparatory to identifying duplicate blocks 1802, the segments 1800 may be evaluated to generate a signature map 1806. The signature map 1806 maps a signature 1808 of a block 1802 to one or more segments 1800 storing blocks 1802 having that signature 1808. In the illustrated example, each signature is mapped to one or more PSIDs 1810 that may identify physical segments 324 on a particular storage device. Other identification approaches may also be used. For example, an entry in the signature map 1806 may include some or all of the VSID, volume ID, and slice ID to which a segment 1802 is allocated, the segment including a block 1802 having the signature 1808 of that entry.

Where segments are de-duplicated across multiple devices, a device identifier may further be included and indicate the storage location of each segment mapped to a signature 1808 in the signature map 1806.

The signatures 1808 may be in the form of hashes of blocks 1802. In some embodiments, the hashes are much smaller than the blocks they represent, e.g. a 32 byte or larger value to represent a 4 kB block. For example, a hashing algorithm such as SHA 256 may be used. Accordingly, it may be possible for blocks 1802 to be different and have the same signature. However, using hashes to identify potential matches reduces the number of blocks 1802 that need to be compared to one another. For example, once all the blocks 1802 with identical hashes are identified, the blocks 1802 may be compared byte by byte to determine whether they are in fact identical.

FIG. 18B illustrates how the segments 1800 may be modified upon identifying duplicated blocks 1802. In particular, blocks 1802 of those segments 1800 having at least one block 1802 that is a duplicate are copied to pool segments 1812. For each duplicated block 1802, only one copy of that block is copied to the pool segments 1812.

One or more of the segments 1800 containing duplicated blocks are changed to pool metadata segments 1814. In particular, the metadata 1804 of one or more first duplicated segments 1800 may be copied into a second duplicated segments and the one or more first duplicated segments 1800 may then be deleted. The metadata 1804 in the pool metadata segments may be modified such that the entries 1816 refer to the pool segment 1812 and physical offset at which the data corresponding to that metadata entry 1804 is written. For example, LBA A1 is included in segment S1 at physical offset P1 within segment S1. If a block of data B1 at P1 is found to be duplicative, all the blocks of S1 are copied to a pool segment PS1 such that one copy of the block B1 is written to PS1 at physical offset P2.

In a first scenario, segment S1 is converted to a pool metadata segment. In that case, the metadata entry for LBA A1 at physical offset P1 may be modified or rewritten such that LBA A1 is now matched to an identifier of pool segment P1 and includes the physical offset P2.

In another scenario, a different segment S2 is converted to the pool metadata segment. In that case, a metadata entry is created in segment S2 for LBA A1 and includes an identifier of pool segment P1 and includes the physical offset P2.

In some embodiments, metadata entries are consolidated into a common pool segment only for those segments assigned to the same logical storage volume or to the same slice of a logical storage volume. In contrast, the pool segments 1812 may store data from any number of slices or logical storage volumes in some embodiments.

Referring back to FIG. 3 while still referring to FIG. 18B, in some embodiments, the segment map 314 may include entries for pool segments 182. For example, the slice ID field may be set to be an identifier indicating that that a particular PSID 316 is assigned as a pool segment. Likewise, a segment that is designated as a pool metadata segment may be identified as such. Alternatively, the segment map 300 may remain unmodified since the pool metadata segment remains assigned to the same slice identifier 310.

As noted above, segments are assigned monotonically increasing VSIDs 318 upon allocation and these are used to determine which segment stores the latest data for an LBA. Accordingly, the metadata entries 316 in a pool metadata segment may be rewritten to include the VSID of the segment from which the metadata entry was obtained. In this manner, although metadata entries from multiple segments are written to the same pool metadata segment, the metadata entry with the highest VSID contains the latest version of data for an LBA. The ordering of metadata entries may also be retained, i.e. metadata entries copied from an original segment to a pool metadata segment may be written in the same order in which they were in the original segment. In this manner, if the same LBA was written to repeatedly in the same segment, the last-written instance may be identified from the ordering as discussed above with respect to FIGS. 3 through 7.

Those segments 1800 that do not include a duplicated block 1802 may remain unchanged as shown in FIG. 18B.

Referring to FIG. 18C, in some instances, the impact of de-duplication may be reduced by off-loading the identification of duplicates to a cloud computing platform 1818. The cloud computing platform may be embodied as AMAZON WEB SERVICES (AWS), MICROSOFT AZURE, GOOGLE CLOUD, or other cloud computing platform. For example, the segments 1800 may be copied to the storage of the cloud computing platform 1818 as segment copies 1820. The computing resources of the cloud computing platform 1818 may then populate the signature map 1806 and identify duplicate blocks 1802 in the copies 1820 as described above. Pool segments and pool metadata segments may be created in the storage of the cloud computing platform 1818 in the same manner described above with respect to FIG. 18B

Those segments having duplicate blocks may then be deleted from storage devices 108 of premise equipment. For example, the cloud computing platform 1818 may indicate to the storage manager 102 or storage node 106 those segments which were found to include duplicate blocks, such as in the form of a listing of PSIDs, a slice ID and VSID pair, or other identifier.

In some instances, pool segments remain on the storage of the cloud computing platform 1818 and copies of the pool metadata segments are copied to the premise storage devices 108. When needed by a storage node 106, the entries of the pool metadata segments point to pool segments on the cloud computing platform 1818 and the storage node 106 may request data from the pool segments or an entire pool segment including requested data. The data or pool segment including the data may then be returned by the cloud computing platform 1818 to the storage node 106.

FIG. 19 illustrates a method 1900 for de-duplicating segments. The method 1900 is executed with respect to a plurality of original segments that may be on the same storage device 108, on storage devices of the same storage node 106, or on storage devices 108 of multiple storage nodes. The plurality of original segments may be allocated to multiple different slice IDs and/or multiple logical volume IDs. The method 1900 is presumed to be executed by a storage node 106 or other computer system on the same premise as the storage devices 108 storing the plurality of segments, e.g. the same data center or office building.

In some embodiments, the method 1900 is only executed with respect to segments that are not excepted from the de-duplication process based on an explicit designation of a storage volume or slice of a storage volume to which the segments are allocated. A segments allocated to a storage volume or a slice of a storage volume may be excepted based on an automated determination of the usage of that storage volume or slice of a storage volume.

For example, an application may include multiple storage volumes, such as an oracle database with data disks (volumes) and a log disks(volumes). There may be cases that certain volumes need fast read response. In the above example, database log disks need very fast response for faster transaction times. It may also be case that a particular sub-part of the volume, e.g., slice, needs higher read response. Accordingly, such storage volumes or slices of storage volumes may be designated as exempt from deduplication and omitted from processing according to the method 1900.

In another example, certain volumes of an application may be used in such a way that duplicates do not occur or are highly unlikely to occur. Accordingly, trying to find duplicates is a waste of resources. Accordingly, such storage volumes or slices of storage volumes may be identified and exempted from de-duplication according to the method 1900. For example, the method 1900 may be executed a number of times with respect to a storage volume or slice of a storage volume. If a number of duplicates identified is below a threshold for a predetermined number of iterations (1 or more) of the method 1900, the storage volume or slice of a storage volume may be exempted from processing according to the method 1900. In other embodiments, an entire application may be exempted in response to some or all of its storage volumes having below-threshold numbers of duplicates for a pre-determined number of iterations of the method 1900.

The method 1900 may advantageously be executed periodically, rather than continuously, at a point in time at which the storage node 106 is relatively lightly loaded relative to other times, such as nightly, on weekends, or at other times.

The method 1900 may include creating 1902 a signature map. For example, this may include evaluating all the blocks of all of the plurality of segments. For each block (“the subject block”) of the current segment being evaluated (“the subject segment”), a signature (e.g., hash) is calculated. This hash is then compared to any previous entries in the signature table. If the hash matches a previous entry, the previous entry is updated to refer to the subject segment and an offset at which the subject block is stored in the subject segment. The reference to the subject segment may include the PSID of the subject segment, the VSID and slice ID to which the subject segment is mapped in the segment map 314, or some other identifier. Where the method 1900 is performed across multiple devices 108 or storage nodes 106, the subject segment may be identified in the entry by a device ID and/or node ID for the device 108 and storage node 106 on which it is stored.

Accordingly, upon completion of step 1902, the signature map will indicate all pairs of possible matches, i.e., each entry in the signature map that references more than one block indicates a block that is potentially duplicated.

The method 1900 may then include identifying 1904 matching blocks. In particular, for each entry in the signature map referencing multiple blocks, the multiple blocks may be compared. For example, for each possible pairing of blocks among the multiple blocks, the blocks in the pairing may be evaluated to determine whether they are identical, this may include a byte-by-byte comparison. Those blocks in which each and every byte is the same may be determined to be identical. Where the computer system represents values in multiple bytes, e.g., 2, 4, 8 bytes, 2, 4, or 8 bytes may be compared simultaneously. If all comparisons are determined to be identical, then the blocks of the pairing are determined to be identical. As is readily apparent, there may be any number of blocks determined to all be identical to one another.

The method 1900 may then include processing 1906 as “the subject segment” according to steps 1908-1912 those segments referenced in the signature map that include at least one block determined to be identical to another block at step 1904 (at least one “duplicated block”).

Step 1908 may include copying blocks of the subject segment to one or more pool segments. If another segment including a duplicated block in the subject segment has already been copied to the one or more pool segment, the duplicated block in the subject segment is not copied. Step 1908 may include allocating a segment as a current pool segments on a storage device 108, such as by adding an identifier in a field 310, 318, or some other field of a PSID 316 in the segment map 314 for that storage device that was previously free. Blocks of the subject segment may be copied to the current pool segment until it is full at which time another segment may be allocated as the current pool segment and blocks of the subject segment are written to the current pool segment until all blocks (except previously-written duplicated blocks) are written to one or more of the pool segments.

Step 1910 may include modifying the metadata of the subject segment to indicate where the blocks are written to. For the first instance of a duplicated block that is written to a pool segment, the metadata for the duplicated block may include the LBA that the first instance was written to, an identifier (e.g., PSID) of the pool segment to which the first instance was written, and a physical offset within that pool segment at which the first instance was written. Metadata for a non-duplicated block is updated in an identical manner.

For a second or any other subsequent instance of the duplicated block in a same or different segment, the metadata is updated to reference the identifier (e.g., PSID) of the pool segment to which the first instance of that duplicated block was written, and the physical offset within that pool segment at which the first instance was written.

The updated metadata of step 1910 may be written to the metadata of the subject segment or may be written to memory to be persisted at a later time.

Step 1912 may further include consolidating the metadata as modified at step 1910 into pool metadata segments. In particular, for segments identified as having a duplicate block that are assigned to the same logical storage unit (e.g., same slice ID and volume ID), the metadata of those segments may be written to a subset of those segments and those segments that metadata is not written to may be released, e.g., marked as free in the segment map 314. Step 1912 may be performed as each subject segment is processed or may be performed after all subject segments have been processed according to steps 1908 and 1910.

As noted above with respect to FIG. 18B, consolidating may preserve information useful in identifying the latest version of data for an LBA, such as a VSID of the segment from which metadata was copied and the ordering of metadata entries and metadata index pages within the segment from which the metadata was copied. For example, the metadata of the subject segment may be written to a previously-designated pool metadata segment assigned to the same slice ID and volume ID mapped to the subject segment in the segment map 314 if there is room in this pool metadata segment, otherwise the subject segment may be designated as a pool metadata segment for the slice ID and volume ID.

FIG. 20 illustrates a method 2000 that may be executed by premise equipment (storage nodes 106 and storage devices 108 in a common network and housed in a common structure such as a data center or office building) in conjunction with the cloud computing platform 1818. The method 2000 may advantageously be executed periodically at a point in time at which either the premise equipment or cloud computing platform is relatively lightly loaded relative to other times, such as nightly, on weekends, or at other times.

The method 2000 may include copying 2002 the plurality of segments from one or more storage devices 108 coupled to one or more storage nodes 106 to the storage resources of the cloud computing platform 1818. The cloud computing platform 1818 may host software for coordinating the copying 2002 and for performing the de-duplication according to the method 2000. Steps ascribed below to the cloud computing platform 1818 may be performed by executing this software. Copying 2002 may be accompanied with steps or data to maintain intelligibility of the segments, e.g. a mapping that maps the VSID, slice ID, and volume ID mapped to each segment to a storage location on the cloud computing platform at which the each segment is stored. Copying 2002 may include copying the segments to cheaper, e.g. archival, storage on the cloud computing platform to reduce the cost of performing de-duplication.

The cloud computing platform 1818 may then create 2004 a signature table and identify 2006 matching blocks, such as as described above with respect to steps 1902 and 1904 of the method 1900.

The method 2000 may then include processing 2008 those segments having duplicative blocks as “the subject segment” according to steps 2010-2014. This may include copying 2010 blocks of the subject segment to pool segments, modifying 2012 the metadata of the subject segment, and consolidating 2014 the metadata of the subject segment to pool metadata segments. Steps 2010-2014 may be performed in the same manner as for steps 1908-1912 of the method 1900 except that it is performed using the computing and storage resources of the cloud computing platform. As for the method 1900, the consolidating step 2014 may be performed as each subject segment is processed or after all subject segments have been processed.

The method 2000 may further include transmitting 2016 an instruction from the cloud computing platform 1818 to the storage node 106 hosting the storage device 108 storing the subject segment to delete (e.g., free) the subject segment. For example, the instruction may include the PSID, VSID and volume ID and slice ID, or other identifier or combination of identifiers sufficient to identify the subject segment. For example, at the copying step 2002, each segment may be sent such that some or all of these identifiers and possibly an identifier of the node 106 and storage device 108 on which the segment is stored are associated with the each segment. The identifier or identifiers of each segment may be mapped by the cloud computing platform to an identifier of a location where the each segment is stored. The storage node 106 may respond to the instruction by flagging the PSID mapped to the identifier or identifiers in the instruction by the segment map as being free in the segment map 314.

The method 2000 may further include transmitting 2018 the pool metadata segments to the premise, i.e. some or all of the storage nodes 106. For example, a pool metadata segment for a volume ID and slice ID may be sent to the storage node 106 to which that volume Id and slice ID are assigned. The metadata may reference the pool segments on the cloud computing platform such that the storage node may then access the pool segments using the metadata. For example, each metadata entry may be modified at step 2012 such that it includes an identifier sufficient to uniquely identify the pool segment in which the block of data referenced by the metadata is written on the cloud computing platform and an identifier of the cloud computing platform.

FIG. 21 illustrates an example method 2100 for processing read requests on a storage node 106 where some segments are pool segments and at least some of the pool segments. The method 2100 may be executed by a storage node receiving the read requests in conjunction with the cloud computing platform 1818.

The method 2100 includes receiving 2102 a read request, such as from an application executing on a source of the read request, which may be a compute node 110, the storage node 106, a cloud computing platform, or some other source.

The method 2100 may include evaluating 2104 whether the data referenced by the read request is stored on the cloud computing platform, such as in a pool segment. This may be performed in various ways. In one example, upon receiving the pool metadata segments, the storage node 106 updates the block map 338. For example, the storage node 106 may obtain, from the pool metadata segments, an identifier of the pool segment to which a block of data corresponding to an LBA 332 was written and the physical offset within that pool segment at which the block of data is written. This pool segment identifier and offset may then be added to the entry for that LBA 332 in the block map 338 in place of the PSID 316 and PO 334 formerly included in that entry.

As noted above, the pool metadata segment may preserve VSIDs of segments from which blocks were copied. Accordingly, the storage node 106 may identify those pool metadata segments corresponding to a slice ID and volume ID included in the read request. The storage node 106 may identify those metadata entries in these pool metadata segments that reference an LBA. Those metadata entries referencing the LBA that include the highest VSID may also be identified.

Among those metadata entries referencing the LBA and having the highest VSID, the last written metadata entry may be identified. For example, pool metadata segments may be assigned a pool index that increase monotonically. Metadata from segments may be written to the pool segments in order of the VSIDs to which segments are mapped. Accordingly, the last written metadata entry for an LBA will be the one that is in the highest pool indexed pool metadata segment and is furthest from the second end relative to other metadata entries referencing the LBA, presuming writing starting from the second end as described above with respect to FIG. 3. For example, the last written metadata entry may be the last entry referencing the LBA in the index page 328 referencing the LBA that is furthest from a second end of the physical segment 324 storing the highest pool indexed pool metadata segment having at least one metadata entry referencing the LBA.

In some embodiments, the storage node 106 may provide the block map 338 to the cloud computing platform 1818. When a segment corresponding to a PSID 316 is written to a pool segment, the cloud computing platform 1818 may update each entry including that PSID 316 to reference the pool segment identifier and physical offset to which the data corresponding to the LBA of that entry was written. The cloud computing platform 1818 may then transmit the updated entries for LBAs of a slice to the storage node 106 which then replaces the entries for these LBAs with the updated entries in its block map 338.

The entries of the block map may further include a location field that indicates whether the data for an LBA 332 is on a storage device 108 of the storage node or an identifier of the cloud computing platform 1818. Accordingly, the location field for the each LBA 332 for which the corresponding data is on the cloud computing platform 1818 may be updated to include an identifier of the cloud computing platform 1818. Multiple cloud computing platforms may be used such that the location field is further used to select the cloud computing platform from which to request data.

Accordingly, step 2104 may include evaluating whether the location field for an LBA in the block map 338 for the slice ID and volume ID referenced in the read request references a cloud computing platform 1818. If so, the method 2100 may include requesting copying 2106 of the pool segment referenced in the location field from the cloud computing platform 1818 to a storage device of the storage node 106. The method 2100 may further include updating the pool metadata segments referencing blocks of data stored in the copied pool segment to now reference the copy of the pool segment stored on the storage node 106, e.g., the PSID 316 of a physical segment 324 to which the pool segment was copied. For example, references to a pool segment identifier on the cloud computing device will be replaced with the PSID 316 of the copy stored by the storage node 106.

The read request may then be executed locally 2110 by reading the block of data at the LBA referenced by the read request from the pool segment copied at step 2106. In particular, by reading the block of data from the physical offset within the copied pool segment indicated in the entry of the block map 338 corresponding to the LBA, slice ID, and volume ID referenced in the read request.

Where the last written data block for the LBA, slice ID, and volume ID referenced in the read request is not found 2014 to be stored in the cloud, the read request is executed locally 2110 as well in the same manner described above.

Note that in some embodiments, copying of the pool segment is not performed unless a threshold frequency of read requests are received referencing blocks of data stored in that pool segment. Otherwise, the read request is sent to the cloud computing platform 1818, which uses its copy of the block map 338 to identify the pool segment and physical offset of the block of data corresponding to the LBA, slice ID, and volume ID of the read request and returns the block of data to the source of the read request, e.g., the storage node 106 that forwarded the read request to the cloud computing platform 1818 or the compute node 110 executing the application that issued the read request.

In the case where the method 1900 is executed locally on a storage node, reading may be performed as described in FIG. 21 except that all read requests will be executed 2110 locally and steps 2102-2108 may be omitted. Note further that the block map 338 may be updated to reflect changes in the location of a block storing the last written data for an LBA (“the latest block”) in the same manner as described above: as the latest block is written to a pool segment or is found to be another instance of a block already written to a pool segment, an identifier of the pool segment and the physical offset within the pool segment where the copy of the latest block is written are added to the entry for that LBA in the block map 338 and used to process subsequent read requests as described above with respect to step 2110.

FIG. 22 is a block diagram illustrating an example computing device 2200. Computing device 2200 may be used to perform various procedures, such as those discussed herein. The storage manager 102, storage nodes 106, compute nodes 110, and hybrid nodes, cloud computing platform 1818, or any computing device referenced herein may have some or all of the attributes of the computing device 2200.

Computing device 2200 includes one or more processor(s) 2202, one or more memory device(s) 2204, one or more interface(s) 2206, one or more mass storage device(s) 2208, one or more Input/output (I/O) device(s) 2210, and a display device 2230 all of which are coupled to a bus 2212. Processor(s) 2202 include one or more processors or controllers that execute instructions stored in memory device(s) 2204 and/or mass storage device(s) 2208. Processor(s) 2202 may also include various types of computer-readable media, such as cache memory.

Memory device(s) 2204 include various computer-readable media, such as volatile memory (e.g., random access memory (RAM) 2214) and/or nonvolatile memory (e.g., read-only memory (ROM) 2216). Memory device(s) 2204 may also include rewritable ROM, such as Flash memory.

Mass storage device(s) 2208 include various computer readable media, such as magnetic tapes, magnetic disks, optical disks, solid-state memory (e.g., Flash memory), and so forth. As shown in FIG. 22, a particular mass storage device is a hard disk drive 2224. Various drives may also be included in mass storage device(s) 2208 to enable reading from and/or writing to the various computer readable media. Mass storage device(s) 2208 include removable media 2226 and/or non-removable media.

I/O device(s) 2210 include various devices that allow data and/or other information to be input to or retrieved from computing device 2200. Example I/O device(s) 2210 include cursor control devices, keyboards, keypads, microphones, monitors or other display devices, speakers, printers, network interface cards, modems, lenses, CCDs or other image capture devices, and the like.

Display device 2230 includes any type of device capable of displaying information to one or more users of computing device 2200. Examples of display device 2230 include a monitor, display terminal, video projection device, and the like.

Interface(s) 2206 include various interfaces that allow computing device 2200 to interact with other systems, devices, or computing environments. Example interface(s) 2206 include any number of different network interfaces 2220, such as interfaces to local area networks (LANs), wide area networks (WANs), wireless networks, and the Internet. Other interface(s) include user interface 2218 and peripheral device interface 2222. The interface(s) 2206 may also include one or more peripheral interfaces such as interfaces for printers, pointing devices (mice, track pad, etc.), keyboards, and the like.

Bus 2212 allows processor(s) 2202, memory device(s) 2204, interface(s) 2206, mass storage device(s) 2208, I/O device(s) 2210, and display device 2230 to communicate with one another, as well as other devices or components coupled to bus 2212. Bus 2212 represents one or more of several types of bus structures, such as a system bus, PCI bus, IEEE 1394 bus, USB bus, and so forth.

For purposes of illustration, programs and other executable program components are shown herein as discrete blocks, although it is understood that such programs and components may reside at various times in different storage components of computing device 2200, and are executed by processor(s) 2202. Alternatively, the systems and procedures described herein can be implemented in hardware, or a combination of hardware, software, and/or firmware. For example, one or more application specific integrated circuits (ASICs) can be programmed to carry out one or more of the systems and procedures described herein.

In the above disclosure, reference has been made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific implementations in which the disclosure may be practiced. It is understood that other implementations may be utilized and structural changes may be made without departing from the scope of the present disclosure. References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

Implementations of the systems, devices, and methods disclosed herein may comprise or utilize a special purpose or general-purpose computer including computer hardware, such as, for example, one or more processors and system memory, as discussed herein. Implementations within the scope of the present disclosure may also include physical and other computer-readable media for carrying or storing computer-executable instructions and/or data structures. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer system. Computer-readable media that store computer-executable instructions are computer storage media (devices). Computer-readable media that carry computer-executable instructions are transmission media. Thus, by way of example, and not limitation, implementations of the disclosure can comprise at least two distinctly different kinds of computer-readable media: computer storage media (devices) and transmission media.

Computer storage media (devices) includes RAM, ROM, EEPROM, CD-ROM, solid state drives (“SSDs”) (e.g., based on RAM), Flash memory, phase-change memory (“PCM”), other types of memory, other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer.

An implementation of the devices, systems, and methods disclosed herein may communicate over a computer network. A “network” is defined as one or more data links that enable the transport of electronic data between computer systems and/or modules and/or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a transmission medium. Transmissions media can include a network and/or data links, which can be used to carry desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above should also be included within the scope of computer-readable media.

Computer-executable instructions comprise, for example, instructions and data which, when executed at a processor, cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or acts described above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

Those skilled in the art will appreciate that the disclosure may be practiced in network computing environments with many types of computer system configurations, including, an in-dash vehicle computer, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, pagers, routers, switches, various storage devices, and the like. The disclosure may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

Further, where appropriate, functions described herein can be performed in one or more of: hardware, software, firmware, digital components, or analog components. For example, one or more application specific integrated circuits (ASICs) can be programmed to carry out one or more of the systems and procedures described herein. Certain terms are used throughout the description and claims to refer to particular system components. As one skilled in the art will appreciate, components may be referred to by different names. This document does not intend to distinguish between components that differ in name, but not function.

It should be noted that the sensor embodiments discussed above may comprise computer hardware, software, firmware, or any combination thereof to perform at least a portion of their functions. For example, a sensor may include computer code configured to be executed in one or more processors, and may include hardware logic/electrical circuitry controlled by the computer code. These example devices are provided herein purposes of illustration, and are not intended to be limiting. Embodiments of the present disclosure may be implemented in further types of devices, as would be known to persons skilled in the relevant art(s).

At least some embodiments of the disclosure have been directed to computer program products comprising such logic (e.g., in the form of software) stored on any computer useable medium. Such software, when executed in one or more data processing devices, causes a device to operate as described herein.

While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. The foregoing description has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Further, it should be noted that any or all of the aforementioned alternate implementations may be used in any combination desired to form additional hybrid implementations of the disclosure. 

1. A method comprising: providing a plurality of segments stored on one or more storage devices coupled to a computer system, each segment of the plurality of segments including a plurality of data blocks and a metadata section including a plurality of metadata entries, each data block of the plurality data blocks having a corresponding metadata entry of the plurality of entries including a logical address for the each data block and an offset within the each segment at which the each data block is written; (a) identifying, by an evaluating system, a plurality of duplicated blocks, each block of the plurality of duplicated blocks having at least two identical copies among the plurality of data blocks of the plurality of segments, the evaluating computer system being one of the computer system and a different computer system; (b) for each matched segment of the plurality of matched segments, the matched segments being segments of the plurality of segments having a data block of the plurality of data blocks thereof that is one of the plurality of duplicated blocks: copying the blocks of the each matched segment to one of a plurality of pool segments; and providing a pool metadata segment of a plurality of pool metadata segments storing data from the metadata section of the each matched segment.
 2. The method of claim 1, wherein providing the pool data segment for one or more first segments of the matched segments comprises designating the one or more first segments as the pool metadata segment.
 3. The method of claim 2, wherein providing the pool data segment for one or more second segments of the matched segments comprises: copying at least a portion of the metadata sections of the one or second segments to the one or more first segments.
 4. The method of claim 3, wherein providing the pool data segment for each second segment of the one or more second segments comprises: identifying one of the first segments that is assigned to a same logical storage unit as the each second segment; and copying the at least the portion of the metadata section of the each second segment to the one of the first segments.
 5. The method of claim 1, wherein the evaluating computer system is a cloud computing platform.
 6. The method of claim 5, further comprising: copying the plurality of segments to the cloud computing platform to obtain a plurality of cloud segments; and performing (a) and (b) on the plurality of cloud segments.
 7. The method of claim 6, further comprising: after performing (a) and (b), instructing the computer system to delete the matched segments from the one or more storage devices.
 8. The method of claim 7, further comprising: modifying each pool metadata segment of the plurality of pool metadata segments to reference one or more of the plurality of pool segments to obtain a plurality of modified pool metadata segments, the plurality of pool segments being stored on the cloud computing platform; and transmitting the plurality of modified pool metadata segments to the computer system.
 9. The method of claim 8, further comprising: detecting, by the computer system, a request to read data in the plurality of pool segments; and identifying, by the computer system, a pool segment referenced by the request according to the plurality of metadata segments.
 10. The method of claim 9, further comprising, in response to the request, at least one of: requesting, by the computer system, transfer of the pool segment referenced by the request; and requesting, by the computer system, reading of data from the pool segment referenced by the request.
 11. A system comprising a cloud computing platform including storage resources and computation resources, the computation resources programmed to: receive a plurality of segments, each segment of the plurality of segments including a plurality of data blocks and a metadata section including a plurality of metadata entries, each data block of the plurality data blocks having a corresponding metadata entry of the plurality of entries including a logical address for the each data block and an offset within the each segment at which the each data block is written; (a) identify a plurality of duplicated blocks, each block of the plurality of duplicated blocks having at least two identical copies among the plurality of data blocks of the plurality of segments; (b) for each matched segment of the plurality of matched segments, the matched segments being segments of the plurality of segments having a data block of the plurality of data blocks thereof that is one of the plurality of duplicated blocks: copy the blocks of the each matched segment to one of a plurality of pool segments; and provide a pool metadata segment of a plurality of pool metadata segments storing data from the metadata section of the each matched segment.
 12. The system of claim 11, wherein the computation resources are programmed to provide the pool data segment for one or more first segments of the matched segments by designating the one or more first segments as the pool metadata segment.
 13. The system of claim 12, wherein the computation resources are programmed to provide the pool data segment for one or more second segments of the matched segments by: copying the data from the metadata sections of the one or second segments to the one or more first segments.
 14. The system of claim 3, wherein the computation resources are programmed to provide the pool data segment for each second segment of the one or more second segments by: identifying one of the first segments that is assigned to a same logical storage unit as the each second segment; and copying the data from the metadata section of the each second segment to the one of the first segments.
 15. The system of claim 11, wherein the computation resources are programmed to: copy the plurality of metadata segments to a source device from from the cloud computing platform from which the plurality of segments were received without copying the plurality of pool segments to the source device.
 16. The system of claim 11, wherein the computation resources are programmed to: instructing a source device to delete the matched segments, the plurality of segments being received from the source device.
 17. The system of claim 16, wherein the computation resources are further programmed to: modify each pool metadata segment of the plurality of pool metadata segments to reference one or more of the plurality of pool segments to obtain a plurality of modified pool metadata segments; and transmit the plurality of modified pool metadata segments to the computer system.
 18. The system of claim 17, wherein the computation resources are further programmed to: detect a request to read data in the plurality of pool segments; identify a pool segment referenced by the request according to the plurality of metadata segments; and return the pool segment to a source of the request.
 19. The system of claim 17, wherein the computation resources are further programmed to: detect a request to read data in the plurality of pool segments; identify a pool segment referenced by the request according to the plurality of metadata segments; retrieve the data from the pool segment referenced by the request; and return the data to a source of the request. 